[Mr V]

The bigger question is why you would want to use resistors on the minbot, do you want a slow bot? Shunting the motor leads together will make it act as a dynamic brake to slow the descent nicely. The kop limit SW or a household 3 way SW will do it. Diagrams on how to wire it are all over CD. If your bot stays at the top of the power you can use a 4 way SW to reverse 1 motor and put the other in brake mode.